In brief:
Unlikely

While anything is possible the circumstance you describe would require several very unlikely things occurring to allow for pregnancy, including sperm surviving on the showerhead, live sperm being transferred to your hand when you touch the showerhead, and then live sperm being transferred to your vagina and then finding their way into your uterus/etc for pregnancy.

This would be very unlikely.

In brief:
Unlikely

While anything is possible the circumstance you describe would require several very unlikely things occurring to allow for pregnancy, including sperm surviving on the showerhead, live sperm being transferred to your hand when you touch the showerhead, and then live sperm being transferred to your vagina and then finding their way into your uterus/etc for pregnancy.

This would be very unlikely.
Would you like to video or text chat with me?